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<FONT color="green">001</FONT>    /*<a name="line.1"></a>
<FONT color="green">002</FONT>     * Licensed to the Apache Software Foundation (ASF) under one or more<a name="line.2"></a>
<FONT color="green">003</FONT>     * contributor license agreements.  See the NOTICE file distributed with<a name="line.3"></a>
<FONT color="green">004</FONT>     * this work for additional information regarding copyright ownership.<a name="line.4"></a>
<FONT color="green">005</FONT>     * The ASF licenses this file to You under the Apache License, Version 2.0<a name="line.5"></a>
<FONT color="green">006</FONT>     * (the "License"); you may not use this file except in compliance with<a name="line.6"></a>
<FONT color="green">007</FONT>     * the License.  You may obtain a copy of the License at<a name="line.7"></a>
<FONT color="green">008</FONT>     *<a name="line.8"></a>
<FONT color="green">009</FONT>     *      http://www.apache.org/licenses/LICENSE-2.0<a name="line.9"></a>
<FONT color="green">010</FONT>     *<a name="line.10"></a>
<FONT color="green">011</FONT>     * Unless required by applicable law or agreed to in writing, software<a name="line.11"></a>
<FONT color="green">012</FONT>     * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.12"></a>
<FONT color="green">013</FONT>     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.13"></a>
<FONT color="green">014</FONT>     * See the License for the specific language governing permissions and<a name="line.14"></a>
<FONT color="green">015</FONT>     * limitations under the License.<a name="line.15"></a>
<FONT color="green">016</FONT>     */<a name="line.16"></a>
<FONT color="green">017</FONT>    package org.apache.commons.math3.optim.nonlinear.scalar.noderiv;<a name="line.17"></a>
<FONT color="green">018</FONT>    <a name="line.18"></a>
<FONT color="green">019</FONT>    import java.util.Comparator;<a name="line.19"></a>
<FONT color="green">020</FONT>    <a name="line.20"></a>
<FONT color="green">021</FONT>    import org.apache.commons.math3.optim.PointValuePair;<a name="line.21"></a>
<FONT color="green">022</FONT>    import org.apache.commons.math3.analysis.MultivariateFunction;<a name="line.22"></a>
<FONT color="green">023</FONT>    <a name="line.23"></a>
<FONT color="green">024</FONT>    /**<a name="line.24"></a>
<FONT color="green">025</FONT>     * This class implements the Nelder-Mead simplex algorithm.<a name="line.25"></a>
<FONT color="green">026</FONT>     *<a name="line.26"></a>
<FONT color="green">027</FONT>     * @version $Id: NelderMeadSimplex.java 1364392 2012-07-22 18:27:12Z tn $<a name="line.27"></a>
<FONT color="green">028</FONT>     * @since 3.0<a name="line.28"></a>
<FONT color="green">029</FONT>     */<a name="line.29"></a>
<FONT color="green">030</FONT>    public class NelderMeadSimplex extends AbstractSimplex {<a name="line.30"></a>
<FONT color="green">031</FONT>        /** Default value for {@link #rho}: {@value}. */<a name="line.31"></a>
<FONT color="green">032</FONT>        private static final double DEFAULT_RHO = 1;<a name="line.32"></a>
<FONT color="green">033</FONT>        /** Default value for {@link #khi}: {@value}. */<a name="line.33"></a>
<FONT color="green">034</FONT>        private static final double DEFAULT_KHI = 2;<a name="line.34"></a>
<FONT color="green">035</FONT>        /** Default value for {@link #gamma}: {@value}. */<a name="line.35"></a>
<FONT color="green">036</FONT>        private static final double DEFAULT_GAMMA = 0.5;<a name="line.36"></a>
<FONT color="green">037</FONT>        /** Default value for {@link #sigma}: {@value}. */<a name="line.37"></a>
<FONT color="green">038</FONT>        private static final double DEFAULT_SIGMA = 0.5;<a name="line.38"></a>
<FONT color="green">039</FONT>        /** Reflection coefficient. */<a name="line.39"></a>
<FONT color="green">040</FONT>        private final double rho;<a name="line.40"></a>
<FONT color="green">041</FONT>        /** Expansion coefficient. */<a name="line.41"></a>
<FONT color="green">042</FONT>        private final double khi;<a name="line.42"></a>
<FONT color="green">043</FONT>        /** Contraction coefficient. */<a name="line.43"></a>
<FONT color="green">044</FONT>        private final double gamma;<a name="line.44"></a>
<FONT color="green">045</FONT>        /** Shrinkage coefficient. */<a name="line.45"></a>
<FONT color="green">046</FONT>        private final double sigma;<a name="line.46"></a>
<FONT color="green">047</FONT>    <a name="line.47"></a>
<FONT color="green">048</FONT>        /**<a name="line.48"></a>
<FONT color="green">049</FONT>         * Build a Nelder-Mead simplex with default coefficients.<a name="line.49"></a>
<FONT color="green">050</FONT>         * The default coefficients are 1.0 for rho, 2.0 for khi and 0.5<a name="line.50"></a>
<FONT color="green">051</FONT>         * for both gamma and sigma.<a name="line.51"></a>
<FONT color="green">052</FONT>         *<a name="line.52"></a>
<FONT color="green">053</FONT>         * @param n Dimension of the simplex.<a name="line.53"></a>
<FONT color="green">054</FONT>         */<a name="line.54"></a>
<FONT color="green">055</FONT>        public NelderMeadSimplex(final int n) {<a name="line.55"></a>
<FONT color="green">056</FONT>            this(n, 1d);<a name="line.56"></a>
<FONT color="green">057</FONT>        }<a name="line.57"></a>
<FONT color="green">058</FONT>    <a name="line.58"></a>
<FONT color="green">059</FONT>        /**<a name="line.59"></a>
<FONT color="green">060</FONT>         * Build a Nelder-Mead simplex with default coefficients.<a name="line.60"></a>
<FONT color="green">061</FONT>         * The default coefficients are 1.0 for rho, 2.0 for khi and 0.5<a name="line.61"></a>
<FONT color="green">062</FONT>         * for both gamma and sigma.<a name="line.62"></a>
<FONT color="green">063</FONT>         *<a name="line.63"></a>
<FONT color="green">064</FONT>         * @param n Dimension of the simplex.<a name="line.64"></a>
<FONT color="green">065</FONT>         * @param sideLength Length of the sides of the default (hypercube)<a name="line.65"></a>
<FONT color="green">066</FONT>         * simplex. See {@link AbstractSimplex#AbstractSimplex(int,double)}.<a name="line.66"></a>
<FONT color="green">067</FONT>         */<a name="line.67"></a>
<FONT color="green">068</FONT>        public NelderMeadSimplex(final int n, double sideLength) {<a name="line.68"></a>
<FONT color="green">069</FONT>            this(n, sideLength,<a name="line.69"></a>
<FONT color="green">070</FONT>                 DEFAULT_RHO, DEFAULT_KHI, DEFAULT_GAMMA, DEFAULT_SIGMA);<a name="line.70"></a>
<FONT color="green">071</FONT>        }<a name="line.71"></a>
<FONT color="green">072</FONT>    <a name="line.72"></a>
<FONT color="green">073</FONT>        /**<a name="line.73"></a>
<FONT color="green">074</FONT>         * Build a Nelder-Mead simplex with specified coefficients.<a name="line.74"></a>
<FONT color="green">075</FONT>         *<a name="line.75"></a>
<FONT color="green">076</FONT>         * @param n Dimension of the simplex. See<a name="line.76"></a>
<FONT color="green">077</FONT>         * {@link AbstractSimplex#AbstractSimplex(int,double)}.<a name="line.77"></a>
<FONT color="green">078</FONT>         * @param sideLength Length of the sides of the default (hypercube)<a name="line.78"></a>
<FONT color="green">079</FONT>         * simplex. See {@link AbstractSimplex#AbstractSimplex(int,double)}.<a name="line.79"></a>
<FONT color="green">080</FONT>         * @param rho Reflection coefficient.<a name="line.80"></a>
<FONT color="green">081</FONT>         * @param khi Expansion coefficient.<a name="line.81"></a>
<FONT color="green">082</FONT>         * @param gamma Contraction coefficient.<a name="line.82"></a>
<FONT color="green">083</FONT>         * @param sigma Shrinkage coefficient.<a name="line.83"></a>
<FONT color="green">084</FONT>         */<a name="line.84"></a>
<FONT color="green">085</FONT>        public NelderMeadSimplex(final int n, double sideLength,<a name="line.85"></a>
<FONT color="green">086</FONT>                                 final double rho, final double khi,<a name="line.86"></a>
<FONT color="green">087</FONT>                                 final double gamma, final double sigma) {<a name="line.87"></a>
<FONT color="green">088</FONT>            super(n, sideLength);<a name="line.88"></a>
<FONT color="green">089</FONT>    <a name="line.89"></a>
<FONT color="green">090</FONT>            this.rho = rho;<a name="line.90"></a>
<FONT color="green">091</FONT>            this.khi = khi;<a name="line.91"></a>
<FONT color="green">092</FONT>            this.gamma = gamma;<a name="line.92"></a>
<FONT color="green">093</FONT>            this.sigma = sigma;<a name="line.93"></a>
<FONT color="green">094</FONT>        }<a name="line.94"></a>
<FONT color="green">095</FONT>    <a name="line.95"></a>
<FONT color="green">096</FONT>        /**<a name="line.96"></a>
<FONT color="green">097</FONT>         * Build a Nelder-Mead simplex with specified coefficients.<a name="line.97"></a>
<FONT color="green">098</FONT>         *<a name="line.98"></a>
<FONT color="green">099</FONT>         * @param n Dimension of the simplex. See<a name="line.99"></a>
<FONT color="green">100</FONT>         * {@link AbstractSimplex#AbstractSimplex(int)}.<a name="line.100"></a>
<FONT color="green">101</FONT>         * @param rho Reflection coefficient.<a name="line.101"></a>
<FONT color="green">102</FONT>         * @param khi Expansion coefficient.<a name="line.102"></a>
<FONT color="green">103</FONT>         * @param gamma Contraction coefficient.<a name="line.103"></a>
<FONT color="green">104</FONT>         * @param sigma Shrinkage coefficient.<a name="line.104"></a>
<FONT color="green">105</FONT>         */<a name="line.105"></a>
<FONT color="green">106</FONT>        public NelderMeadSimplex(final int n,<a name="line.106"></a>
<FONT color="green">107</FONT>                                 final double rho, final double khi,<a name="line.107"></a>
<FONT color="green">108</FONT>                                 final double gamma, final double sigma) {<a name="line.108"></a>
<FONT color="green">109</FONT>            this(n, 1d, rho, khi, gamma, sigma);<a name="line.109"></a>
<FONT color="green">110</FONT>        }<a name="line.110"></a>
<FONT color="green">111</FONT>    <a name="line.111"></a>
<FONT color="green">112</FONT>        /**<a name="line.112"></a>
<FONT color="green">113</FONT>         * Build a Nelder-Mead simplex with default coefficients.<a name="line.113"></a>
<FONT color="green">114</FONT>         * The default coefficients are 1.0 for rho, 2.0 for khi and 0.5<a name="line.114"></a>
<FONT color="green">115</FONT>         * for both gamma and sigma.<a name="line.115"></a>
<FONT color="green">116</FONT>         *<a name="line.116"></a>
<FONT color="green">117</FONT>         * @param steps Steps along the canonical axes representing box edges.<a name="line.117"></a>
<FONT color="green">118</FONT>         * They may be negative but not zero. See<a name="line.118"></a>
<FONT color="green">119</FONT>         */<a name="line.119"></a>
<FONT color="green">120</FONT>        public NelderMeadSimplex(final double[] steps) {<a name="line.120"></a>
<FONT color="green">121</FONT>            this(steps, DEFAULT_RHO, DEFAULT_KHI, DEFAULT_GAMMA, DEFAULT_SIGMA);<a name="line.121"></a>
<FONT color="green">122</FONT>        }<a name="line.122"></a>
<FONT color="green">123</FONT>    <a name="line.123"></a>
<FONT color="green">124</FONT>        /**<a name="line.124"></a>
<FONT color="green">125</FONT>         * Build a Nelder-Mead simplex with specified coefficients.<a name="line.125"></a>
<FONT color="green">126</FONT>         *<a name="line.126"></a>
<FONT color="green">127</FONT>         * @param steps Steps along the canonical axes representing box edges.<a name="line.127"></a>
<FONT color="green">128</FONT>         * They may be negative but not zero. See<a name="line.128"></a>
<FONT color="green">129</FONT>         * {@link AbstractSimplex#AbstractSimplex(double[])}.<a name="line.129"></a>
<FONT color="green">130</FONT>         * @param rho Reflection coefficient.<a name="line.130"></a>
<FONT color="green">131</FONT>         * @param khi Expansion coefficient.<a name="line.131"></a>
<FONT color="green">132</FONT>         * @param gamma Contraction coefficient.<a name="line.132"></a>
<FONT color="green">133</FONT>         * @param sigma Shrinkage coefficient.<a name="line.133"></a>
<FONT color="green">134</FONT>         * @throws IllegalArgumentException if one of the steps is zero.<a name="line.134"></a>
<FONT color="green">135</FONT>         */<a name="line.135"></a>
<FONT color="green">136</FONT>        public NelderMeadSimplex(final double[] steps,<a name="line.136"></a>
<FONT color="green">137</FONT>                                 final double rho, final double khi,<a name="line.137"></a>
<FONT color="green">138</FONT>                                 final double gamma, final double sigma) {<a name="line.138"></a>
<FONT color="green">139</FONT>            super(steps);<a name="line.139"></a>
<FONT color="green">140</FONT>    <a name="line.140"></a>
<FONT color="green">141</FONT>            this.rho = rho;<a name="line.141"></a>
<FONT color="green">142</FONT>            this.khi = khi;<a name="line.142"></a>
<FONT color="green">143</FONT>            this.gamma = gamma;<a name="line.143"></a>
<FONT color="green">144</FONT>            this.sigma = sigma;<a name="line.144"></a>
<FONT color="green">145</FONT>        }<a name="line.145"></a>
<FONT color="green">146</FONT>    <a name="line.146"></a>
<FONT color="green">147</FONT>        /**<a name="line.147"></a>
<FONT color="green">148</FONT>         * Build a Nelder-Mead simplex with default coefficients.<a name="line.148"></a>
<FONT color="green">149</FONT>         * The default coefficients are 1.0 for rho, 2.0 for khi and 0.5<a name="line.149"></a>
<FONT color="green">150</FONT>         * for both gamma and sigma.<a name="line.150"></a>
<FONT color="green">151</FONT>         *<a name="line.151"></a>
<FONT color="green">152</FONT>         * @param referenceSimplex Reference simplex. See<a name="line.152"></a>
<FONT color="green">153</FONT>         * {@link AbstractSimplex#AbstractSimplex(double[][])}.<a name="line.153"></a>
<FONT color="green">154</FONT>         */<a name="line.154"></a>
<FONT color="green">155</FONT>        public NelderMeadSimplex(final double[][] referenceSimplex) {<a name="line.155"></a>
<FONT color="green">156</FONT>            this(referenceSimplex, DEFAULT_RHO, DEFAULT_KHI, DEFAULT_GAMMA, DEFAULT_SIGMA);<a name="line.156"></a>
<FONT color="green">157</FONT>        }<a name="line.157"></a>
<FONT color="green">158</FONT>    <a name="line.158"></a>
<FONT color="green">159</FONT>        /**<a name="line.159"></a>
<FONT color="green">160</FONT>         * Build a Nelder-Mead simplex with specified coefficients.<a name="line.160"></a>
<FONT color="green">161</FONT>         *<a name="line.161"></a>
<FONT color="green">162</FONT>         * @param referenceSimplex Reference simplex. See<a name="line.162"></a>
<FONT color="green">163</FONT>         * {@link AbstractSimplex#AbstractSimplex(double[][])}.<a name="line.163"></a>
<FONT color="green">164</FONT>         * @param rho Reflection coefficient.<a name="line.164"></a>
<FONT color="green">165</FONT>         * @param khi Expansion coefficient.<a name="line.165"></a>
<FONT color="green">166</FONT>         * @param gamma Contraction coefficient.<a name="line.166"></a>
<FONT color="green">167</FONT>         * @param sigma Shrinkage coefficient.<a name="line.167"></a>
<FONT color="green">168</FONT>         * @throws org.apache.commons.math3.exception.NotStrictlyPositiveException<a name="line.168"></a>
<FONT color="green">169</FONT>         * if the reference simplex does not contain at least one point.<a name="line.169"></a>
<FONT color="green">170</FONT>         * @throws org.apache.commons.math3.exception.DimensionMismatchException<a name="line.170"></a>
<FONT color="green">171</FONT>         * if there is a dimension mismatch in the reference simplex.<a name="line.171"></a>
<FONT color="green">172</FONT>         */<a name="line.172"></a>
<FONT color="green">173</FONT>        public NelderMeadSimplex(final double[][] referenceSimplex,<a name="line.173"></a>
<FONT color="green">174</FONT>                                 final double rho, final double khi,<a name="line.174"></a>
<FONT color="green">175</FONT>                                 final double gamma, final double sigma) {<a name="line.175"></a>
<FONT color="green">176</FONT>            super(referenceSimplex);<a name="line.176"></a>
<FONT color="green">177</FONT>    <a name="line.177"></a>
<FONT color="green">178</FONT>            this.rho = rho;<a name="line.178"></a>
<FONT color="green">179</FONT>            this.khi = khi;<a name="line.179"></a>
<FONT color="green">180</FONT>            this.gamma = gamma;<a name="line.180"></a>
<FONT color="green">181</FONT>            this.sigma = sigma;<a name="line.181"></a>
<FONT color="green">182</FONT>        }<a name="line.182"></a>
<FONT color="green">183</FONT>    <a name="line.183"></a>
<FONT color="green">184</FONT>        /** {@inheritDoc} */<a name="line.184"></a>
<FONT color="green">185</FONT>        @Override<a name="line.185"></a>
<FONT color="green">186</FONT>        public void iterate(final MultivariateFunction evaluationFunction,<a name="line.186"></a>
<FONT color="green">187</FONT>                            final Comparator&lt;PointValuePair&gt; comparator) {<a name="line.187"></a>
<FONT color="green">188</FONT>            // The simplex has n + 1 points if dimension is n.<a name="line.188"></a>
<FONT color="green">189</FONT>            final int n = getDimension();<a name="line.189"></a>
<FONT color="green">190</FONT>    <a name="line.190"></a>
<FONT color="green">191</FONT>            // Interesting values.<a name="line.191"></a>
<FONT color="green">192</FONT>            final PointValuePair best = getPoint(0);<a name="line.192"></a>
<FONT color="green">193</FONT>            final PointValuePair secondBest = getPoint(n - 1);<a name="line.193"></a>
<FONT color="green">194</FONT>            final PointValuePair worst = getPoint(n);<a name="line.194"></a>
<FONT color="green">195</FONT>            final double[] xWorst = worst.getPointRef();<a name="line.195"></a>
<FONT color="green">196</FONT>    <a name="line.196"></a>
<FONT color="green">197</FONT>            // Compute the centroid of the best vertices (dismissing the worst<a name="line.197"></a>
<FONT color="green">198</FONT>            // point at index n).<a name="line.198"></a>
<FONT color="green">199</FONT>            final double[] centroid = new double[n];<a name="line.199"></a>
<FONT color="green">200</FONT>            for (int i = 0; i &lt; n; i++) {<a name="line.200"></a>
<FONT color="green">201</FONT>                final double[] x = getPoint(i).getPointRef();<a name="line.201"></a>
<FONT color="green">202</FONT>                for (int j = 0; j &lt; n; j++) {<a name="line.202"></a>
<FONT color="green">203</FONT>                    centroid[j] += x[j];<a name="line.203"></a>
<FONT color="green">204</FONT>                }<a name="line.204"></a>
<FONT color="green">205</FONT>            }<a name="line.205"></a>
<FONT color="green">206</FONT>            final double scaling = 1.0 / n;<a name="line.206"></a>
<FONT color="green">207</FONT>            for (int j = 0; j &lt; n; j++) {<a name="line.207"></a>
<FONT color="green">208</FONT>                centroid[j] *= scaling;<a name="line.208"></a>
<FONT color="green">209</FONT>            }<a name="line.209"></a>
<FONT color="green">210</FONT>    <a name="line.210"></a>
<FONT color="green">211</FONT>            // compute the reflection point<a name="line.211"></a>
<FONT color="green">212</FONT>            final double[] xR = new double[n];<a name="line.212"></a>
<FONT color="green">213</FONT>            for (int j = 0; j &lt; n; j++) {<a name="line.213"></a>
<FONT color="green">214</FONT>                xR[j] = centroid[j] + rho * (centroid[j] - xWorst[j]);<a name="line.214"></a>
<FONT color="green">215</FONT>            }<a name="line.215"></a>
<FONT color="green">216</FONT>            final PointValuePair reflected<a name="line.216"></a>
<FONT color="green">217</FONT>                = new PointValuePair(xR, evaluationFunction.value(xR), false);<a name="line.217"></a>
<FONT color="green">218</FONT>    <a name="line.218"></a>
<FONT color="green">219</FONT>            if (comparator.compare(best, reflected) &lt;= 0 &amp;&amp;<a name="line.219"></a>
<FONT color="green">220</FONT>                comparator.compare(reflected, secondBest) &lt; 0) {<a name="line.220"></a>
<FONT color="green">221</FONT>                // Accept the reflected point.<a name="line.221"></a>
<FONT color="green">222</FONT>                replaceWorstPoint(reflected, comparator);<a name="line.222"></a>
<FONT color="green">223</FONT>            } else if (comparator.compare(reflected, best) &lt; 0) {<a name="line.223"></a>
<FONT color="green">224</FONT>                // Compute the expansion point.<a name="line.224"></a>
<FONT color="green">225</FONT>                final double[] xE = new double[n];<a name="line.225"></a>
<FONT color="green">226</FONT>                for (int j = 0; j &lt; n; j++) {<a name="line.226"></a>
<FONT color="green">227</FONT>                    xE[j] = centroid[j] + khi * (xR[j] - centroid[j]);<a name="line.227"></a>
<FONT color="green">228</FONT>                }<a name="line.228"></a>
<FONT color="green">229</FONT>                final PointValuePair expanded<a name="line.229"></a>
<FONT color="green">230</FONT>                    = new PointValuePair(xE, evaluationFunction.value(xE), false);<a name="line.230"></a>
<FONT color="green">231</FONT>    <a name="line.231"></a>
<FONT color="green">232</FONT>                if (comparator.compare(expanded, reflected) &lt; 0) {<a name="line.232"></a>
<FONT color="green">233</FONT>                    // Accept the expansion point.<a name="line.233"></a>
<FONT color="green">234</FONT>                    replaceWorstPoint(expanded, comparator);<a name="line.234"></a>
<FONT color="green">235</FONT>                } else {<a name="line.235"></a>
<FONT color="green">236</FONT>                    // Accept the reflected point.<a name="line.236"></a>
<FONT color="green">237</FONT>                    replaceWorstPoint(reflected, comparator);<a name="line.237"></a>
<FONT color="green">238</FONT>                }<a name="line.238"></a>
<FONT color="green">239</FONT>            } else {<a name="line.239"></a>
<FONT color="green">240</FONT>                if (comparator.compare(reflected, worst) &lt; 0) {<a name="line.240"></a>
<FONT color="green">241</FONT>                    // Perform an outside contraction.<a name="line.241"></a>
<FONT color="green">242</FONT>                    final double[] xC = new double[n];<a name="line.242"></a>
<FONT color="green">243</FONT>                    for (int j = 0; j &lt; n; j++) {<a name="line.243"></a>
<FONT color="green">244</FONT>                        xC[j] = centroid[j] + gamma * (xR[j] - centroid[j]);<a name="line.244"></a>
<FONT color="green">245</FONT>                    }<a name="line.245"></a>
<FONT color="green">246</FONT>                    final PointValuePair outContracted<a name="line.246"></a>
<FONT color="green">247</FONT>                        = new PointValuePair(xC, evaluationFunction.value(xC), false);<a name="line.247"></a>
<FONT color="green">248</FONT>                    if (comparator.compare(outContracted, reflected) &lt;= 0) {<a name="line.248"></a>
<FONT color="green">249</FONT>                        // Accept the contraction point.<a name="line.249"></a>
<FONT color="green">250</FONT>                        replaceWorstPoint(outContracted, comparator);<a name="line.250"></a>
<FONT color="green">251</FONT>                        return;<a name="line.251"></a>
<FONT color="green">252</FONT>                    }<a name="line.252"></a>
<FONT color="green">253</FONT>                } else {<a name="line.253"></a>
<FONT color="green">254</FONT>                    // Perform an inside contraction.<a name="line.254"></a>
<FONT color="green">255</FONT>                    final double[] xC = new double[n];<a name="line.255"></a>
<FONT color="green">256</FONT>                    for (int j = 0; j &lt; n; j++) {<a name="line.256"></a>
<FONT color="green">257</FONT>                        xC[j] = centroid[j] - gamma * (centroid[j] - xWorst[j]);<a name="line.257"></a>
<FONT color="green">258</FONT>                    }<a name="line.258"></a>
<FONT color="green">259</FONT>                    final PointValuePair inContracted<a name="line.259"></a>
<FONT color="green">260</FONT>                        = new PointValuePair(xC, evaluationFunction.value(xC), false);<a name="line.260"></a>
<FONT color="green">261</FONT>    <a name="line.261"></a>
<FONT color="green">262</FONT>                    if (comparator.compare(inContracted, worst) &lt; 0) {<a name="line.262"></a>
<FONT color="green">263</FONT>                        // Accept the contraction point.<a name="line.263"></a>
<FONT color="green">264</FONT>                        replaceWorstPoint(inContracted, comparator);<a name="line.264"></a>
<FONT color="green">265</FONT>                        return;<a name="line.265"></a>
<FONT color="green">266</FONT>                    }<a name="line.266"></a>
<FONT color="green">267</FONT>                }<a name="line.267"></a>
<FONT color="green">268</FONT>    <a name="line.268"></a>
<FONT color="green">269</FONT>                // Perform a shrink.<a name="line.269"></a>
<FONT color="green">270</FONT>                final double[] xSmallest = getPoint(0).getPointRef();<a name="line.270"></a>
<FONT color="green">271</FONT>                for (int i = 1; i &lt;= n; i++) {<a name="line.271"></a>
<FONT color="green">272</FONT>                    final double[] x = getPoint(i).getPoint();<a name="line.272"></a>
<FONT color="green">273</FONT>                    for (int j = 0; j &lt; n; j++) {<a name="line.273"></a>
<FONT color="green">274</FONT>                        x[j] = xSmallest[j] + sigma * (x[j] - xSmallest[j]);<a name="line.274"></a>
<FONT color="green">275</FONT>                    }<a name="line.275"></a>
<FONT color="green">276</FONT>                    setPoint(i, new PointValuePair(x, Double.NaN, false));<a name="line.276"></a>
<FONT color="green">277</FONT>                }<a name="line.277"></a>
<FONT color="green">278</FONT>                evaluate(evaluationFunction, comparator);<a name="line.278"></a>
<FONT color="green">279</FONT>            }<a name="line.279"></a>
<FONT color="green">280</FONT>        }<a name="line.280"></a>
<FONT color="green">281</FONT>    }<a name="line.281"></a>




























































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